This invention generally pertains to a manifold used in a chemical delivery system.
The chemicals used in the fabrication of integrated circuits must have a ultrahigh purity to allow satisfactory process yields. As integrated circuits have decreased in size, there has been a directly proportional increase in the need for maintaining the purity of source chemicals. This is because contaminants are more likely to deleteriously affect the electrical properties of integrated circuits as line spacing and interlayer dielectric thickness decrease.
One ultrahigh purity chemical used in the fabrication of integrated circuits is tetraethylorthosilicate (TEOS). TEOS has been widely used in integrated circuit manufacturing operations such as chemical vapor deposition (CVD) to form silicon dioxide films. These conformal films are generated upon the molecular decomposition of TEOS at elevated temperatures in plasma enhanced and atmospheric pressure reactors (PECVD, APCVD). TEOS is typically used for undoped, and phosphorous and boron doped interlayer dielectrics, intermetal dielectrics, sidewall spacers, and trench filling applications.
Integrated circuit fabricators typically require TEOS with 99.999999+% purity with respect to trace metals. Overall, the TEOS must exhibit a 99.99+% purity. This high degree of purity is necessary to maintain satisfactory process yields. However, it also necessitates the use of special equipment to contain and deliver the high purity TEOS to the CVD reaction chamber.
Traditionally, high purity TEOS (and dopants) has been fed to the CVD reaction chamber from a small volume container called an ampule. More recently, stainless steel containers have been developed, such as described in U.S. Pat. Nos. 5,45,766; 5,562,132; and 5,607,002. The present inventors have discovered that the manifold system disclosed in these patents which was designed for materials of known physical properties and not acutely toxic were needed to be changed to accommodate other, more agressive chemicals. In addition, the present inventors have sought to improve on the fail safe nature of the system. The present inventors have thus determined that a need exists for an improved manifold for use in the refill systems such as described in the above-referenced patents.